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Raspberry Pi (Zero) as JTAG Programmer

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I was thinking of creating a pcb to mount the mcus and have some in circuit jtag adapter for the mps430 on a Raspberry.

Should I only use the GIPO headers of the RPi or should I create a circuity to programm the msp430 (maybe other mcus as well).


Thanks a lot for your advice


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I thought this would be dead in the water due to the PI's slow direct IO speed. But that's likely not the case.


SBW is the programming interface for all the modern MSP430's. The interface is described in this TI document (SLAU320) http://www.ti.com/lit/ug/slau320v/slau320v.pdf

The SBW interface serial communication uses time-division multiplexing and allocates three time slots: TMS_SLOT, TDI_SLOT, and TDO_SLOT. 
To clock TCLK through the SBW interface in a similar method as it is clocked through TDI during 4-wire JTAG access, an alternative JTAG timing method is implemented. 
This implementation makes use of the fact that the TDI and TMS signals are captured with the rising edge of SBWTCK in their respective slots as shown in Figure 1-8.

Since the SBW statemachine is clocked from the SBWTCK pin you could theoretically run it at a slower speed than a ezFET does. Ofcourse this means it takes longer to program. But doable.



Some additional points of interest


  • The pi has USB... Why not attach a ezFET lite programmer via USB, use mspdebug and call it a day?
  • The ezFET enumerates as a Serial device, it may be possible to alter the code and run it directly from the PI's UART channel.
  • If you don't require debugging I would suggest implementing a bootloader, and just running that over UART or SPI. It would require much less effort.

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